Answer:
500
Explanation:
Out of every 15 people, there are 12 people who prefer eating at restaurants which means that 80% of people (12/15=.8) prefer eating out.
If 400 selected eating at restaurants in a survey, this accounts for 80% of the people that voted.
We can simplify this now to 20%=100 people because 80% is also four-fifths of 100% and the remaining one-fifth will equal 100 people. (400/4=100)
Since the remaining 20% is 100 people, we can do 400+100= 500 people that participated in the survey.